This invention relates to a straightly extensible measuring tape which can maintain a straight extension when it is extended longer.
Out of various kinds of measuring tapes there are measuring tapes which are made of a metal material and provided with a curvature portion to a width direction relative to an extensible direction of the tape. However, the length of a straight extension of the measuring tape is very short. According to a conventional measuring tape of the above structure, the length of the measuring tape which can maintain a straight extension is normally no more than about several ten centimeters. In order to overcome the above disadvantage, there is on the market a measuring tape in which its width is widened up to a degree of 25 mm, its thickness is increased a little bit and its curvature rate is about 26.phi. at an arc section to a width direction when the measuring tape is extended. This measuring tape maintains a straight extension of more than 1 meter in case it is extended from an opening of a measuring case, but its disadvantage is that the measuring tape itself becomes larger and the measuring device becomes heavier.
In view of the above disadvantage of a conventional art, this invention has been achieved.